Introduction to The Decision Model

The Decision Model is based on seminal  book The Decision Model: A Business Logic Framework Linking Business and Technology by Barbarba von Halle and Larry Goldberg. Both Larry and Barbara are Managing Partners at Knowledge Partners International ( KPI is an acknowledged world leader in Business Rules since its inception in 1996.

In fact I have got so excited about this technology that I have found a way to link The Decision Model with GPUs (Graphical Processing Units – one of my favourite topics for supercomputing) for what I am calling Accelerated Business Decisions but more about that in a subsequent post.

The Decision Model defines a new way to model business rules and business logic using a well defined technology independent structure that is based on the inherent nature of logic and which has been extended by normalisation and integrity principles.

The best way to gain an insight into the motivation behind TDM is to consider data modelling before the Relational Model. At that time data modelling was based on the technology used to implement data and its interrelationships such Network (e.g. IDMS Codasyl), Hierarchical (e.g. IBM IMS) and Extended Network (e.g. MDBS III).  However this was to change when E. F. Codd developed the Relational Model and introduced the Three Normal Forms that permitted data to be modelled independently of implementation technology using the inherent relationships within data.  This enabled Relational Data Models to become real corporate assets independent of the applications using the data.  In the same way TDM is revolutionising business rules and business logic within the enterprise.

The key concepts within The Decision Model can be viewed from a top-down perspective as follows:

  1. Identify the relevant business decisions within a business domain.  Typically a business decision is a conclusion that a business arrives at through business logic and which it wants to manage.
  2. Now for each business decision identify and model the set of rule families and their interrelationships that contains the business logic required to reach each business decision.
  3. These rule families have a passing resemblance to decision tables however these are no ordinary decision table and must follow 15  Decision Model Principles which are split into Structural Principles (determine structural simplicity); Declarative Principles (provide declarative structure) and Integrity Principles (providing optimal logical integrity)


These 15 Principles ensure that the Decision Model is aligned with its business purpose and introduces the concept of normalisation (TDM defines 1NF, 2NF, 3N similar to the Relational Model) that ensures that there are no logical errors within the business logic.

A Rule Family is a two dimensional table with the following characteristics:

  1. The is one and only one conclusion fact type for example “Person likelihood of defaulting on a loan
  2. Can have as many conditions as required in a row (even zero)
  3. All conditions are Anded together
  4. There are no ORs, ELSEs, BUTs, OTHERWISE – these are what has caused serious logical errors in other approaches to modelling business logic.
  5. There are NO actions within the conclusion (Actions are modelled and implemented at the BPM layer – see forthcoming blog post on The Decision Model & BPM) however Messages are available to pass meta-information as required.


Now interrelationships between Rule Families are created where the conclusion of one Rule Family is a condition within another Rule Family and these interrelationships are also required to follow the Decision Model  Inferential Integrity Principles.

Since a picture is said to be worth a thousand words TDM has defined a graphical notation that reduces the complexity of understanding and modelling large decision models – see the diagram below for a partial TDM model using the TDM graphical notation.



The blue  octagon represents the business decision “Determine Policy Renewal Method” (from the insurance domain) and it is linked to a rule family whose conclusion is the same as the business decision for this business logic model.

Rule families are represented by green tabbed rectangles and the rule family conditions are listed within.  The conditions that are between main line and the dashed line represent those conditions that are inferentially linked to other rule families – because these conditions are conclusions within the other rule families. The diagram shows that the Policy Pricing Within Bounds condition within the Policy  Renewal Method rule family is linked to the Policy Pricing Within Bounds rule family and is showing by a linking relationship between the two rule families.

Those conditions below the dashed line represents  conditions that do not logically depend on the conclusions from other rule families.

The actual rules within a rule family is shown by the yellow table in the diagram.  There is a lot more to the Decision Notation that shown in this diagram and also a decision model diagram must also comply with the 15 Principles. The diagram below shows the high level Decision Model for the “Determine Policy Renewal Method“.



To help model and manage large enterprise  TDM projects, including full life-cycle management, tools such as DECISION from Sapiens ( offer an excellent solution.  Other TDM tool vendors are  New Wisdom Software ( and Open Rules( are also available.  A subsequent blog post will explore these tools in greater detail.

How to experiment and learn The Decision Model

Over the coming years The Decision Model is expected to have a similar impact on business logic as the Relational Model had on data.  It is not possible in a short post such as this to outline the full power of TDM however I would recommend reading a primer on The Decision Model, a version of which can be found at

Also there is a Decision Model Live primer version that uses the open source OpenRules to demonstrate the key concepts of the Decision Model at You can download an evaluation of the open source Business Decision Management System from OpenRules  ( and run through the Decision Model Live Primer.

However to truly understand TDM and its impact on IT and the business you should read “The Decision Model” book and it is available on Amazon at


Getting The Decision Model Professional Services

KPI has developed a number of TDM consultancy services, TDM best practices, training and certification services and KPI as appointed a number of certified consulting partners who can provide  KPI Decision Model FirstSTEP, KPISTEP, STEPment consulting services outside the USA and they are:

Posted by Suleiman Shehu, CEO, Azinta Systems